Oligomeric isoflavonoids. Part 1. Structure and synthesis of the first (2,3′)-isoflavone-isoflavan dimer

Abstract

The structure and stereochemistry of a novel [2,3′]-isoflavone-isoflavan oligomer, 2′,7-dihydroxy-2-[(3S)-6′,7-dihydroxy-4′-methoxyisoflavan-3′-yl]-4′-methoxyisoflavone (1; R = H), from Dalbergia nitidula are established by synthesis. The strategy of condensation of a C₁₆ to C₁₄ moiety, i.e. C-5′ formylated isoflavan (21) to a 2-hydroxydeoxybenzoin (23) in a modified Baker-Venkataraman approach, should provide general access to this novel class of C-2 coupled oligomeric Isoflavonoids.